1. Field of the Invention
The present invention relates to lenses, and particularly relates to micro-lens arrays.
2. Background of the Related Art
Micro-lens arrays have found increasing application in a wide variety of fields, from ophthalmology through displays. Individual lenses, or lenslets, in the arrays can have sizes ranging from 1 μm to 10 mm in diameter.
In many applications, it is desirable to produce micro-lens arrays in which a mask or field stop is aligned with the lenses. The mask may include a plurality of apertures that are aligned with the individual lenses in the array. The purpose of such a mask may include reducing crosstalk or interference between the images created by each lenslet, or modifying or improving the optical characteristics and performance of the lenslets by altering the affective aperture. Masks can also be useful in reducing reflected light and improving the contrast of the images created by the array.
Given the potentially large number of lenses in micro-lens array, and the micron-scale size of the lenses in some applications, it is very difficult to effectively and precisely align the pattern of apertures in the mask with the exit pupils of the lenses. Currently available techniques include registration of the mask with the lens array using fiducials or similar methods borrowed from semiconductor mask or printing technology. These techniques are difficult to employ accurately over large areas and are time-consuming and expensive.
Alternative methods involve applying mask material to the lens array using an adhesive cured by exposure to ultraviolet light.